1. Field of the Invention
This invention relates generally to truss rods for stringed instruments such as guitars and mandolins, and more specifically to an improved double-action truss rod enabling true two-way adjustment.
2. Description of the Prior Art
A truss rod (also known as an internal stiffener) may be installed into a channel in the neck of a stringed instrument to counteract forward warp or bow caused, e.g., by string tension. Prior art truss rods typically utilize parallel segments of square bar and round bar, welded together at one end, and fitted with a threaded nut on the other end of the round bar adjacent a fixed block on the other end of the square bar so that turning of the nut causes the relative length of one side of the truss to shorten, thereby bending the truss and therefore the neck of the instrument. However, in this structural arrangement, the truss rod bends in one direction only, thereby limiting the possible adjustments that can be made to the neck of the instrument.